Production of new compositions of matter by the esterification of cellulosic material



,i 1" crn ms AT A ymnitsininanal was, mana ed, at; l

. ,signor of one-half .to The Cellulose Acetate Silk om an it l s s r E la d. a

"NoDrawing. Application 0ctober-28,1933,Serial No. 695,725.- In Great Britain November 3,

" {This inyentionrelates to the production of new jth'e esterification of ing the outerthreads. In this known processr ln endeavouris made superficially, to a'cetylate all the material treated to thesame degree. d r

The invention consistsirin subjecting cellulosic material toian. acetylating :treatment so. controlled that the resultant product is a homogeneous mass comprising a mixture of completely acetylated and partly acetylatedcellulose material, the latter retaining in part .the originalcellulose fibre structure and being 'uniformlyadistributed throughout the 111258; .41? x- Q ,=The. product obtained "ac'cordingto the-j-inv, tion may; if desired, rzbe fripened in the usual way, so that thekportion .ofjthe cellulosic material which has been acetylated shows the required degree of solubility inworganic'solvent media.

Products of this nature; inpwhich the cellulosic material is in. part completely. acetylated and: in part superficially 'acetylated, 'canbe used in conjunction with: the usual resinous organic or mine eralifillers, gelatinizing agents'and the like, in

the preparation of-'-p1astic compositions (and moulding-powderswhicmin the. presence of suitable solvents; and/or by the application of heat and pressure, yieldicompact and rigidmasses or translucent or opaque =filmsior sheets. These depend for their. cohesive 'force onxthe cellulose ester present. The unacetylated cellulosic. mate.- rial present functions as a binder and re-enforcing medium which impartsiincreased strength and added flexibility to the product. Inthis respect it is far superior to known mechanical mixtures of cellulose ester and fibrous filler, such as cotton flock, asbestos fibre, and the like, since the gelatinous surface of the residual fibre actually unites or coalesces with the gelatinous ents of the plastic composition.

100 lbs". bleached cotton linters," wood pulp, or paper, ar'e'gradually added with constant stirring to a mixture of 300 lbs. acetic anhydride 9 1 95 ",*400 lbs. glacialfaceticj acid and 540% concentrated sulphuric acid whichjhas previously been cooled tof0 C." ,The'temperature, which is maintained as", low as possible by the application ofbrine'icooling for several hours, will showgrad ual rise. When it has reached a maximum, which should not exceed35 C., afurther addition of 40 lbs'. ofcotton linters, wood-pulp, or paper 'is made and'the reaction allowedto proceed with constant stirringand the application of cooling for about 3 hours, oruntil the added .cellulosic material has been superficially acetylated. 20 lbs. of water is then gradually added withconstant mixing, care v being. again taken to keep the temperature o f the mass as low aspossible. The mixture is then ripened in the usual mannerby allow+ ing it to stand at 20-25" for 44 hours, or until the number of ways. For example, instead of adding f i RoDUorIoN 0Fmwyeomosiermssor I l g MATTER BYTTHE ESTERIFIQATION"0E n ir "cellulosic'material at an intermediate stage of the process, the, additional material. may be incorporated in the starting mass, being thenin a knownexcess in relation tothe amount ofacetyIating agentpresent; Alternatively, the cellulosic material-may be initially introduced in excess and a subsequentadditionmay-be made at an intermediate stageof theprocess. l

e The same result may be obtained by following the normal acetylation procedure but reducing the duration of theireactionand/or the reaction temperature; "Some of the cellulose fibres will suffer complete acetylation; otherswillsufier only superficial change. Here again it is essential that sufiicient time is allowed for the complete superficial acetylation of the cellulose fibres.

p This modification may be further modified by adding cellulosic material to thereaction mass,

sufficient time being allowed for superficial acetylation of such addition.

In a further modification further cellulosic materialmay be added after acetylation proper is complete, but prior to the hydrolysis of the residthe required degree of solubility in organic solvents. If so desired the product may be sepv arated unripened at the end of the primary stage, precipitated, washed'free' from acid and dried.

In all the methods enumerated some or all of the organic solvent diluentmaybefreplaced b an crganicnonsolvent diluent. The acetylation may be facilitated by pro-treat- 'ment of the cellulosic materialgby any known methodf M l The material prepared according to the invention may be cast into films, or pressed into blocks from which sheets can be cut in the known -manner. :7

The new materiaL'admixedwith suitable solvents, plasticizers and fillers in the well known manner, yields thermoplastic moulding compositions which have greater strength than corre- I spending compositions prepared fromthe commercial acetone-soluble cellulose acetate.

The productobtained according to the present .inventiom'when incorporated with the solvents, plasticizers, fillers," pigments, and the like, usual inthe cellulose industryfmaybe cast into films, andQjitQis; found that films are produced. having a velvet matt surface, that'is to say the surface hasan appearance between that of a highly polished surface obtained when using ordinary cellulose esteryand the matt surface obtained by a sp'e'cial method'of casting the ordinary cellulose ester; This special surface 'is obtained by adapting jthe ordinary'me'thod of casting the film, that is to say'by; removing thefilm from the band on 'whicli'itis "before it is thoroughly dry. If itis desired forone surface of the filmto be of a highly polished nature, it is allowed "to remain on, the band on which it is cast until it is thorou hl dry. '1

The material can also be usedinter'alia in the-production ofsplinterless] glass, as the intermediatecementing layer. It is found that in this applicationjof the new material a frosted appearanceis given to the laminated structure. a V

Thef'newmaterialhas=alsoa special application'as an insulating ma'terial'for wrapping conducting wires and the like. The advantage of this application resides in' the fact that the film is not transparent, with the result thatitis easy "fo'r.t he operator to wind the film on to the 'con- (motor in such a way as to avoid overlapping or uneven wrapping, because the edges of the film are easily visible to the operat'o'r, Furthermore it has been found that the electrical insulating ing velvet matt surface for the preparation of compositions suitable for coating fabrics and other materials, for example in the manufacture of leather substitutes.

.What I claim and desire to secure by Letters Patent is:-

1. Process for the production of a new composition of matter consisting in subjecting cellulosic material to an acetylation treatment, the cellulosic material being in excess to that theoretically required for completecacetylation so that on the completion of the reaction there remains some cellulosic material which is only partly acetylated, the latter retaining in part the original cellulose fibrous structure and be ing uniformly distributed throughout the mass.

2. Process as claimed in claim 1 consisting in following the normal acetylation procedure but reducing the duration of some of the reaction and/or the reaction temperature but allowing sufiicient time for the complete acetylation of the cellulose fibres, so. that in the resulting mass some of the cellulosic material is only partly acetylated, and adding a further quantity of cellulosic material to the reaction mass allowing s'ufficient time for superficial acetylation of the added material.

3. Process as claimed in claim 1 consisting in adding cellulosic mat'erialin excess of requirements at an intermediate stage of the process, and when the cellulosicmaterial initially added has been completely acetylated and passed into solution.

4. Process as claimed in claim. 1 further consisting in initially introducing all of the cellulosic material in excess into the acetylating liquid so that apart of the cellulosic material will be only partly acetylated. 1

5'. Process as claimed in.claim 1 further consisting in initially introducing cellulosic material into the reaction mass in excess of that required for complete conversion, and subsequently adding a'furtherquantity of cellulosic material at an intermediate stage of the process.

-6. Processes claimed in claim 1 whereinfurther cellulosic material is added after the acetylation proper is complete, but'prior to'the hydrolysis of the residual acetylating agent.

7. Process as claimed in claim 1 wherein fur-ither' cellulosic material is added after the acetylation proper is complete, but prior to the hydrolysis of the residual acetylating agent; the

carbon tetrachloride and the like.-

9. A new composition of matter comprising a mixture of completely acetylated and partly acetylated cellulosic material having uniformly distributed throughout its mass part of the original cellulose fibrous structure of the partly acetylated cellulosic material.

VICTOR EMMANUEL .YARSLEY. 

